<!DOCTYPE html>
<html lang="en">
<head>
    <link rel="stylesheet" type="text/css" href="css/index.css">
    <meta charset="UTF-8">
    <title>Title</title>
    <div id="main-div">
        111
    </div>
    <div id="back-test">
        222
    </div>
    <div id="index-a">
        <a  href="page/border-test.html" > 边框练习 </a>
    </div>
</head>
<body>
</body>
</html>